Boards and broadcasters believe that, by being played from Thursday to Sunday - like golf tournaments - tests would be easier for fans to watch. They would also take up less time in the sport's overcrowded schedule.
While four-day tests are likely to become more common, the International Cricket Council has confirmed that all matches in the new World Test Championship - which launches with the Ashes series next summer - will be played over five days.
For the foreseeable future, four-day tests are likely to take place only if the match involves Afghanistan, Ireland or Zimbabwe, the three test nations not included in the nine-team championship.
Ireland will view the proposed fixture as a seminal moment in their cricketing history. They were granted test status last year - the match against Pakistan last month was their inaugural test, and they impressed in losing by five wickets.
The ICC approved four-day tests last year. Revised playing conditions include 98 overs per day - rather than 90 in five-day tests. They also allow the follow-on to be enforced if a side have a first-innings lead of 150 runs, rather than 200 in the five-day form.